Breathing Blunt Nose for Drag Reduction at a Supersonic Mach Number

A new concept termed as Breathing Blunt Nose (BBN) is proposed for drag reduction in supersonic flow regime. The experimental investigation has been carried out with a blunt nosed model with and without breathing nose. This thesis presents the results and the physics behind the process which results in the reduction of pressure drag of blunt nosed body by the passive control in form of breathing nose at a supersonic Mach number. The drag of a blunt nosed body with and without breathing nose at Mach 1.96 are compared. The breathing nose is found to reduce the drag on the body by manipulating the high pressure at the nose and the low pressure at the base simultaneously. The shock at the nose of the body becomes weaker when the hole at the nose is open. Direct measurement of drag and the pressure at the nose and at the surface downstream of the nose has been carried out. Flow field around the body with and without breathing nose has been visualized with shadowgraph. A maximum drag reduction of 21% was obtained at NPR 2. This is because of the combined effect of the decrease of high pressure at the nose and increase of low pressure at the base, due to the breathing through the nose hole.